1. Field of the Invention
The present invention relates to a method and apparatus for introducing a solution into a cooling apparatus. In particular, although not exclusively, the present invention relates to a method and apparatus for removing heat from a heat source.
2. The Prior Art
Heat exchangers are often used to remove excess heat from industrial processes. Typical heat exchangers include shell and tube-type heat exchangers, which comprise a length of tubing partially enclosed within a housing or shell. An industrial process stream containing excess heat is introduced into the tubing, whilst a coolant, such as water, is passed through the shell via a separate inlet and outlet. The water removes excess heat from the process stream. Thus, the water exiting the shell is at a higher temperature than the coolant entering the shell. The heated water stream is cooled in a cooling tower before it is recirculated back through the shell. In this way, heat removal can be carried out in a continuous manner.
Most cooling towers contain a porous filler material, known as decking (packing). Water is introduced into the top of the cooling tower and drips down through the decking, whilst air is blown through the decking, causing some of the water to evaporate. The loss of heat by evaporation (evaporative cooling) lowers the remaining water temperature. The cooled water is recirculated to the heat exchanger.
As evaporation occurs, contaminants, such as dissolved solids, build up in the recirculating water. Such contaminants can cause fouling, for example, as a result of biological growth, scale formation, corrosion and/or sludge deposition. The contaminant level may be reduced by removing a portion of the recirculating water from the system. The removal of water in this manner is known as blowdown.
To replace the total water loss from the system, make-up water is introduced. The make-up water is treated with, for example, scale inhibitors, corrosion inhibitors, biocides and dispersants. These additives tend to be expensive and have to be added continuously to the make-up water, adding to the cost of the overall process.
The water quality of the cooling system has a significant effect on the thermal efficiency and life of the cooling tower and heat exchangers.
In an air-cooler, warm air from the surroundings is blown through wet decking or packing material. Heat from the air is transferred to the wet decking material, causing the water contained in the decking to evaporate. As a result, air emerging from the cooler is at a lower temperature than air introduced into the cooler. As the water evaporates, contaminants in the water may deposit on the decking material. Such deposits have a detrimental effect on the thermal efficiency and life of the air-cooler.